This is the fourth of four parts about resilient cities and adaptive law. Read part 1, part 2, and part 3 here.) 

In a recent Environmental Law Reporter article, “Adaptive Law and Resilience,” resilience scientist Lance Gunderson and I have identified aspects of the U.S. legal system that are maladaptive to interconnected nonlinear change in social systems and ecosystems and offered an alternative view of an adaptive legal system.  This blog addresses three aspects of law that are relevant to cities and their resilience: local governance, private property rights, and adaptation.

Resilient cities will need to develop new or reformed legal and policy tools in order to enhance their adaptive capacity.  One improvement, already practiced by some cities, would be to adopt policies that aim for the resilience of multiple systems and component parts, recognizing the potential for failure of one to affect the others – a concept that Gunderson and I call “poly-resilience.”  Thus, we cannot just focus on the vitality of our parks while our streams are degraded or make one neighborhood thrive while another is vulnerable and declining.  Thinking adaptively about poly-resilience requires acknowledging uncertainty and avoiding brushing off potential future risk based on past data or optimistic assumptions.  For example, cities may be tempted to use historic patterns to underestimate the potential for significantly expanding flood areas due to increased frequency and intensity of storm events and altered terrain.  If planners and developers locate high-density, mixed-use, transit-oriented green buildings with native landscaping in these new potential flood zones, they are creating communities that are vulnerable and unsustainable, despite the sustainability and resilience of the basic design concept.  Creating green infrastructure with invasive species that change, and ultimately weaken, the entire vegetated landscape of the region is another example of a maladaptive “green” policy.

One way for cities to take proactive steps towards enhancing their resilience is to adopt “co-benefits” strategies, which achieve multiple, ancillary benefits from a particular approach:  “The multiplicity and diversity of co-benefits aid the resilience of multiple systems and subsystems.  For example, local ordinances protecting and enhancing the urban tree canopy produce many co-benefits.  Urban trees mitigate urban heat island effects (thus helping to save human lives in extreme heat), sequester carbon, moderate stormwater runoff, stabilize soils and prevent erosion, shelter wildlife, maintain temperatures in urban streams, contribute to the walkability of urbanscapes, add economic value to land, improve mental health, enhance area aesthetics, build human connectivity to nature, and provide many other ecological and social benefits.” (p. 10432)

Urban trees are multi-benefit green infrastructure supporting the ecological and social-human resilience of cities.
Urban trees are multi-benefit green infrastructure supporting the ecological and social-human resilience of cities.

Cities will also need to engage in adaptive planning and adaptive management.  Resilience-and-law scholars give importance to adaptive management, which is an iterative process of management that assumes that all knowledge is provisional and engages in a series of experiments that have feedback loops consisting of continuous monitoring, learning, and changes to management actions based on the lessons learned.  Instead of planning all management actions on the “front end” based on extensive, deliberative pre-action study, management evolves as managers “learn while doing.”  Although adaptive management is practiced, albeit often incompletely, by federal agency officials managing forests, wetlands, river systems, and the like, there is clearly a need for many city officials to develop their skills, capacity, and commitment to engage in adaptive management.  For example, green infrastructure strategies might be ill-adapted to climate change, with its changes in growing seasons and ranges, temperatures, precipitation, pests and invasives, and the like.  Local green-infrastructure managers will need to experiment with various types of green infrastructure, continuously monitoring and assessing their conditions, making changes to management plans, and even shifting to new or different systems as changed conditions require.  Enhancing the adaptive-management skills and capacity of local officials will require up-front investment of resources, but it will prevent long-term waste.

Nonetheless, cities could be particularly well-suited to using adaptive planning methods, because they regularly engage in urban planning processes.  The adaptive-management model rejects up-front, comprehensive, long-term, static plans, but it tends to give too little attention to the theory and practice of adaptive planning.  “Adaptive planning is an iterative and evolving process of identifying goals and making decisions for future action that are flexible, contemplate uncertainty and multiple possible scenarios, include feedback loops for frequent modification to plans and their implementation, and build planning and management capacity to adapt to change.”  (Arnold, “Adaptive Watershed Planning and Climate Change”, p. 440)  Details about the methods of adaptive planning can be found in the cited article, as can several examples of adaptive watershed or water-supply planning processes aimed at enhancing the resilience of watersheds or public water supplies to the uncertain impacts of climate change.  These planning processes evaluate options under many plausible models and various contingencies, contain multiple goals and criteria for evaluating possible implementation actions, and expressly build in ongoing iterations in the planning and re-planning (adaptation) process.  As with adaptive management, feedback loops are essential to adaptive planning but are not designed and/or used as fully as needed.  In some cities, existing planning laws and processes can be used for adaptive planning, whereas in other cities, revisions to state or local laws will be needed to provide clear authority to engage in adaptive planning.

Perhaps one of the biggest problems that cities will have to tackle, though, is how to get landowners, businesses, and others to make adaptive changes to their already-authorized existing land uses, such as retrofitting their properties with “best management practices” (BMPs), restoring degraded ecosystems, reducing or eliminating harmful behaviors, or agreeing to new and changeable conditions.  Land use law is premised on up-front regulatory decisions that give landowners and developers clarity and certainty about what they are allowed to do with their land, a structure that is maladaptive to unexpected and substantial changes arising from the interconnected effects of individual landowner behavior, ecosystem functioning, and local community conditions.  A growing number of cities are experiencing some success with mandatory BMP retrofits to developed lands, flexible conditions to land-use permits, or time-limited renewable permits that can be changed if conditions change.  However, property law – including the recent takings case Koontz v. St. John’s Water Management District, requiring regulators to justify conditions demanded of landowners under the Nollan essential nexus test and Dolan rough proportionality test – and the culture of private property rights will operate to resist the ongoing adaptive exercise of local land use regulatory authority on private lands.  Landowners, developers, and lawyers will continue to seek up-front certainty of legal rights.  In order for cities, ecosystems, and society to remain resilient, the law will need to become more adaptive, recognizing that the legal system cannot offer a false promise of certainty that will lead to catastrophe and collapse under changing social-ecological conditions.


Tony Arnold is the Boehl Chair in Property and Land Use, Professor of Law, Affiliated Professor of Urban Planning, and Chair of the Center for Land Use and Environmental Responsibility, University of Louisville.  He has recently been named the Associate Dean for Research and Faculty Development at the University of Louisville’s Brandeis School of Law.  He has served as a planning commissioner, member of a task force addressing environmental justice in urban neighborhoods, a land conservation trust board member, and co-chair of the land use, transportation, and urban forestry committee of the Louisville Metropolitan Climate Change Task Force.   Here he is pictured with two former law and urban planning students, looking at urban tree canopy planning documents, along the Louisville Loop Trail, a 100-mile trail system that rings the entire city, linking existing and new parks, civic facilities, diverse neighborhoods, and waterways.  He can be reached at